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Newcastle disease virus (NDV) has negatively affected the poultry industry worldwide. Given that the antigenic similarity of a vaccine strain to a field virus is effective in protection, an immunoinformatics study was performed to examine the similarity between antibody epitopes of classical vaccines and a sub-genotype VII.2 NDV (VII.2 NDV). Considering the role of fusion (F) and hemagglutinin-neuraminidase (HN) proteins in the induction of neutralizing antibodies, the 3D structure of HN and F proteins of the VII.2 NDV and nine vaccine strains were predicted, refined, and validated. Using these structures, linear and conformational antibody epitopes were mapped. Epitope analysis showed distinct results from the evolutionary distance and protein identity analysis and it was found that the range of difference in the number of identical epitopes in relation to F is wider than HN protein. LaSota and B1 vaccine strains showed the least epitope identity to the VII.2 NDV. The V4 and I-2 vaccine strains showed the highest epitope identity with the VII.2 NDV especially in F protein which is important in virus cell-to-cell transmission. In conclusion, excellence of the LaSota vaccine under field condition shows that protection is not just about epitope similarities and especially in the case of live vaccines, the vaccine-induced damage, replicative capacity and tropism of the vaccine strain are important. The prediction of this study may be useful for inactivated vaccines in which the amount of antigen is all that matters.

Endogenous retroviruses (ERVs) are involved in cellular proliferation, pluripotency, tissue-specific remodelling and regulation of developmental processes. These elements are transcriptionally active in mouse and human pre-implantation embryos. Empirical evidence indicates that regulatory networks involved with ERV transcripts are responsible for pluripotency and totipotency at certain stages of mouse and human pre-implantation development. Yet, the expression in pre-implantation bovine embryo remains unidentified. To determine whether two members of bovine endogenous retroviruses, BERV-K1 and BERV-K2, are expressed in the pre-implantation bovine embryo, each embryonic stage developed in vitro and was subjected to RNA release, reverse transcription and quantitative PCR. We found that BERV-K1 and BERV-K2 are expressed throughout different stages of pre-implantation development. The higher level of expression was detected in embryonic blastomeres with totipotent/pluripotent status (two-cell to 16-cell stages), while the more differentiated blastocyst stage showed significantly lower levels of ERVs expression. These findings suggest a possible role for endogenous retroviruses in the establishment of totipotent and pluripotent states in pre-implantation bovine embryo, similar to functions which have been suggested for these elements in human and mouse embryos.

The purpose of this study was to determine the prevalence of bovine leukemia virus (BLV) in Khorasan Razavi and Khorasan Shomali provinces which are the main provinces located in the northeast of Iran. Total number of 429 blood samples were collected from industrial dairy herds. The samples were categorized based on province, age (2-3, 4-6, and 7-10 years old), calving (≤ 2, 3-5, and > 5) and herd size (≤ 100, 101-250, and > 250) and examined by indirect ELISA. The results of this study showed that 109 (25.4%) out of 429 serum samples were BLV seropositive. The BLV prevalence among cattle of dairy herds of Khorasan Razavi and Khorasan Shomali provinces were 29.8% and 1.5%, respectively. The results showed that the number of seropositive animals was increased significantly with the age (p < 0.05). The infection rate in animals 2-3, 4-6 and 7-10 years old were 12.1%, 26.7% and 45.6%, respectively. It was shown that BLV prevalence according to calving ≤ 2, 3-5 and > 5 was 15.5%, 33.0% and 42.9%, respectively, with a significant difference between calving ≤ 2 and > 5 (p < 0.001). The prevalence of BLV among herd size of ≤ 100, 101-250 and > 250 was 19.7%, 14.3% and 42.1%, respectively, which was significantly higher in herds with more than 250 cattle (p < 0.05). This study revealed that BLV infection in dairy herds of northeast of Iran was influenced by geographical location (province), age, calving and herd size.

DNA vaccine represents a powerful approach for prevention of avian H5N1 influenza infection. Yet, DNA vaccine-induced immune responses might be limited by the short duration of antigen expression. As a strategy to enhance adaptive immune responses elicited by a hemagglutinin 5 (H5) DNA vaccine, we explored the effect of co-administration of a DNA encoding X-linked inhibitor of apoptosis protein (XIAP) as a modulator of apoptosis and a stimulator of inflammatory signaling. In cultured cells as early as 24 hours (h), we found that the DNA vaccine encoded H5 antigen was a potent stimulator of apoptosis, and the H5 pro-apoptotic activity was significantly suppressed by the co-expression of full-length XIAP or mutant XIAP (ΔRING). However, full-length XIAP showed a higher potency than mutant XIAP (ΔRING) in the inhibition of H5-induced apoptosis. We also compared the immunizing ability of transmembrane and secretory forms of H5. Mice vaccinated (twice with 3-week intervals) with the secretory form of H5 showed higher hemagglutination inhibition (HI) antibody titers than mice vaccinated with the transmembrane form of H5. Furthermore, co-administration of XIAP with the secretory form of H5 resulted into a stronger antibody response than the transmembrane form of H5. Our findings suggest that in the design of DNA vaccines for a given pro-apoptotic antigen, using an anti-apoptotic molecular adjuvant and the secretory form of antigen may be a greater stimulus to induce immune responses.